Chuck with locking device

ABSTRACT

The chuck with locking device has a ratchet mechanism comprising a toothed ring (5) with asymmetrical teeth (5a) fixed to an outer casing (2), a ratchet ring (9) arranged such that it can slide but not rotate with respect to a base body (1) and provided with tabs (11) or teeth (9a) providing ratchet interlocking elements, a release elastic element arranged under compression between the ratchet ring (9) and the toothed ring (5), a locking ring (7) arranged adjacent to the ratchet ring (9) outside the base body (1) and fixed inside a locking control sleeve (14), a cam groove (8) formed in the locking ring (7), and a pin (13) inserted in the cam groove (8) and in a hole (30) formed in the base body (1). The locking control sleeve (14) moves the locking ring (7) and the ratchet ring (5) between locking and unlocking positions.

TECHNICAL FIELD

The present invention relates to a chuck provided with a locking devicethat can be manually operated by a user for locking the jaws of thechuck in a gripping position, preventing the jaws from looseningregardless of the rotation direction of the chuck.

BACKGROUND OF THE INVENTION

Keyless chucks are known which comprise a base body having a centrallongitudinal axis and connected for rotating with a drive shaft, and anouter casing coupled outside the base body such that it can rotatecoaxially but not move axially with respect to the base body. The outercasing has an axial opening, and a plurality of jaws are arrangedmovably with respect to the outer casing and communicated with the axialopening. A pusher is coupled to the base body by a threaded coupling andfurthermore coupled to the outer casing such that it can slide axiallybut not rotate coaxially. The pusher is operatively coupled with thejaws, such that rotation of the pusher with respect to the base body ina tightening direction moves the jaws towards the central longitudinalaxis to grip a tool, and rotation of the pusher with respect to the basebody in a opposite loosening direction moves the jaws away from thecentral longitudinal axis to release the tool.

However, when keyless chucks of this type are used in machines ormotor-driven power tools with a reversible rotation direction or inhand-powered tools, there is a risk that the jaws will loosen in anunwanted manner if the machine, the power tool or the hand-powered toolis operatively driven in a reverse rotation direction coinciding withthe mentioned loosening direction for loosening the jaws.

To prevent this risk, some known keyless chucks incorporate a lockingdevice that allows locking the jaws in a gripping position. For example,patent document U.S. Pat. No. 8,403,339 B2 discloses a keyless chuck ofthe type described above including a locking device comprising a toothedring that is fixed with respect to the base body and provided with aplurality of asymmetrical teeth having a saw tooth profile, a lockingring coupled outside the outer casing such that it can rotate but notmove axially with respect to the outer casing, and a ratchet ring movingaxially with respect to the outer casing and with respect to the lockingring between axial locking and unlocking positions when the locking ringis rotated coaxially with respect to the base body in cooperation with acam and an elastic element. The ratchet ring has a plurality ofasymmetrical ratchet teeth opposite and conjugated with the asymmetricalteeth of the toothed ring. When the ratchet ring is in the axial lockingposition, the ratchet teeth are coupled with the teeth of the toothedring, blocking relative rotation between the base body and the outercasing in a loosening direction for loosening the grip of the jaws butallowing, by virtue of the asymmetrical profile of the teeth and of theelastic element, relative rotation in a tightening direction fortightening the grip of the jaws, and when the ratchet ring is in theaxial release position, the ratchet teeth are separated and free ofcontact with the toothed ring.

In said patent document U.S. Pat. No. 8,403,339 B2, the elastic elementis arranged such that it permanently pushes the ratchet ring towards theaxial locking position and the cam moves the ratchet ring towards theaxial unlocking position in opposition to the force exerted by theelastic element.

Utility model document ES 1072879 U discloses a chuck including ahybrid-type fitting mechanism combining a self-tightening mechanism witha key mechanism. Nevertheless, this hybrid-type chuck does not include alocking mechanism.

DISCLOSURE OF THE INVENTION

The present invention provides a chuck with locking device comprising abase body having a central longitudinal axis and being connectable forrotating with a drive shaft, an outer casing coupled outside the basebody such that it can rotate coaxially but not move axially with respectto the base body, a plurality of jaws arranged movably with respect tothe base body and the outer casing communicated with an axial openingthereof, and a fitting mechanism linking movements of the outer casingto movements of the jaws, such that rotation of the outer casing withrespect to the base body in a tightening direction moves the jawstowards said central longitudinal axis and rotation of the outer casingwith respect to the base body in an opposite loosening direction movesthe jaws away from the central longitudinal axis.

The chuck of the present invention further comprises a locking deviceincluding a ratchet mechanism operated by a locking control sleeve,which is coupled outside the base body such that it can rotate betweenangular locking and release positions in cooperation with a cam and anelastic element. When the locking control sleeve is in the angularlocking position, the ratchet mechanism blocks relative rotation betweenthe base body and the outer casing in a loosening direction forloosening the grip of the jaws but allows relative rotation in atightening direction for tightening the grip of the jaws, and when thelocking control sleeve is in the angular release position, the ratchetmechanism allows relative rotation between the base body and the outercasing in both directions.

The ratchet mechanism comprises a toothed ring, a ratchet ring and alocking ring. The toothed ring is fixed with respect to the outer casingand has a plurality of asymmetrical teeth located, for example, in aplane perpendicular to the central longitudinal axis or in a conecoaxial with the central longitudinal axis. The ratchet ring is arrangedfacing the toothed ring such that it can slide axially but not rotatecoaxially with respect to the base body. The ratchet ring has an annularbody and one or more tabs or teeth projecting from the annular bodyinclined towards the asymmetrical teeth of the toothed ring. Thementioned elastic element is a releasing elastic element arranged undercompression between the ratchet ring and the toothed ring such that thereleasing elastic element permanently pushes the ratchet ring away fromthe toothed ring.

In one embodiment, the ratchet ring is made of solid material, such as asolid metal, and said teeth of the ratchet ring are complementary to theasymmetrical teeth of the toothed ring. In this embodiment a pressingelastic element is arranged under compression between the ratchet ringand the locking ring to push the ratchet ring to the toothed ring.

In another embodiment, the ratchet ring is made of sheet metal and theannular body has cuts defining said tabs as interlocking elastic tabsprojecting from the annular body inclined towards the asymmetrical teethof the toothed ring. Each of these interlocking elastic tabs has a freeend providing a ratchet pawl.

Whether the ratchet ring is solid material or metal sheet, the lockingring is arranged outside the base body and fixed inside the lockingcontrol sleeve in a position adjacent to the ratchet ring on a sidethereof opposite the toothed ring. When the ratchet ring is made ofmetal sheet, the locking ring has a support surface in contact with theratchet ring.

The mentioned cam comprises a cam groove formed in a wall of the lockingring and a pin inserted in the cam groove and in a hole perpendicular tothe central longitudinal axis formed in the base body. The cam groovedetermines axial movement of the locking ring between axial locking andrelease positions corresponding to the angular locking and releasepositions of the locking control sleeve, respectively, when the lockingring is rotated by the locking control sleeve coaxially with respect tothe base body in cooperation with the cam.

When the locking ring is in the axial locking position, the locking ringpresses the ratchet pawls of the ratchet ring against the toothed ringin opposition to a force exerted by the releasing elastic element, andthe ratchet pawls are coupled with the asymmetrical teeth of the toothedring blocking relative rotation between the base body and the outercasing in a loosening direction for loosening the grip of the jaws butallowing, by virtue of the asymmetrical profile of the teeth and of theelasticity of the interlocking elastic tabs or of the elasticity of thepressing elastic element which pushes the ratchet ring towards thetoothed ring, relative rotation in a tightening direction for tighteningthe grip of the jaws. When the locking ring is in the axial releaseposition, the locking ring allows the force exerted by the releasingelastic element to separate the ratchet pawl from the toothed ring suchthat the outer casing can rotate freely in both directions with respectto the base body.

Preferably, the pin is inserted in the hole of the base body withsliding fit, and the locking control sleeve is externally press coupledonto the locking ring with interference fit. Therefore, an inner surfaceof the locking control sleeve covers the cam groove and retains the pininserted in the cam groove and in the hole of the base body.

In one embodiment, the releasing elastic element is formed by a coilspring arranged around the base body and having a first end supported ina support surface of the ratchet ring located between the interlockingelastic tabs and a central hole of the annular body, and a second endsupported in an annular seat formed in the outer casing between thetoothed ring and the base body.

In another embodiment, the releasing elastic element is formed by one ormore elastic spring tabs formed in the ratchet ring. These elasticspring tabs are defined by additional cuts formed in the annular body ofthe ratchet ring and are bent such that they project from the ratchetring inclined towards the toothed ring. In the absence of externalstresses, each of the elastic spring tabs has a rounded end portionresting on the asymmetrical teeth of the toothed ring. The rounded endportions are arranged at a greater axial distance from the ratchet ringthan the ratchet pawls of the interlocking elastic tabs. Therefore, therounded end portions of the elastic spring tabs rest on the asymmetricalteeth of the toothed ring before the ratchet pawls of the interlockingelastic tabs are coupled with the asymmetrical teeth of the toothedring, and slip over the asymmetrical teeth of the toothed ring when theratchet ring rotates in either of the two directions.

In both embodiments of the sheet metal ratchet ring, the ratchet ring isobtained by press forming or by laser cutting from a spring steel sheetelement.

In one embodiment, the fitting mechanism of the chuck with lockingdevice of the present invention is a keyless-type mechanism known as aself-tightening mechanism, which comprises a pusher coupled by threadingto the base body and arranged operatively coupled with the jaws.Conventionally, chucks provided with a fitting mechanism of this typetend to tighten the bit when they rotate in a first rotation direction,but tend to loosen the bit when they rotate in a second oppositedirection, so they are only suitable for working when rotating in thefirst rotation direction. With the incorporation of the locking deviceof the present invention, the self-tightening chuck having the fittingmechanism tightened to grip a drill bit and the locking device in thelocking position is able to firmly hold the bit and apply torquerotating in both directions, i.e., right-hand rotation, left-handrotation, and alternately right-hand and left-hand reciprocatingrotation, and the locking device prevents slipping of the bit withrespect to the jaws in both right-hand and left-hand rotations.

In another embodiment, the fitting mechanism of the chuck with lockingdevice of the present invention is of a conventional type normally usinga key, which comprises an actuator ring fixed to the outer casing andprovided with screw threads coupled to thread teeth formed in the jaws.However, with the incorporation of the locking device of the presentinvention, the key mechanism is omitted because the locking deviceallows the chuck to firmly hold the bit with the fitting mechanism andapply torque with right-hand rotation, left-hand rotation, andalternately right-hand and left-hand reciprocating rotation.Furthermore, in this embodiment, when high torque is applied with thechuck by rotating in the tightening direction, the locking device allowseasily removing the bit by loosening the chuck by hand.

In yet another embodiment, the fitting mechanism of the chuck withlocking device of the present invention is a hybrid-type fittingmechanism, such as the one described in said utility model document ES1072879 U, combining the self-tightening fitting mechanism with a keymechanism. Since the coupling between the pusher and the base body,which causes the axial movement of the jaws, is a left-hand threadcoupling, when the tool holding the chuck no longer rotates and thedrilling machine keeps trying to rotate to the right, the fittingmechanism self-tightens. The problem resides in that some timesexcessive self-tightening takes place which cannot be loosened by handwithout the aid of a key. This problem is solved with the hybrid chuckwith a combined self-tightening and key mechanism. Furthermore, with theincorporation of the locking device of the present invention, theself-tightening chuck with a key is able to firmly hold the bit andapply torque by rotating in both directions, i.e., right-hand rotation,left-hand rotation, and alternately right-hand and left-handreciprocating rotation.

It is to be pointed out that the locking device and ratchet mechanism ofthe present invention, whether the ratchet ring is solid material ormetal sheet, is compatible with any one of the keyless self-tighteningfitting mechanism, the conventional type fitting mechanism with a key,the conventional type keyless fitting mechanism, and the self-tighteningfitting mechanism with a key.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages will be more fullyunderstood from the following description of the embodiments providedwith a merely illustrative and non-limiting character in reference tothe attached drawings, in which:

FIG. 1 is a partially sectioned side view of a chuck with locking deviceaccording to an embodiment of the present invention;

FIGS. 2 and 3 are front and rear partially exploded perspective views ofthe chuck of FIG. 1;

FIG. 4 is a side view of a locking ring including a cam groove formingpart of the chuck of FIGS. 1 to 3;

FIG. 5 is a section view illustrating the asymmetrical tooth profile ofa toothed ring forming part of the chuck of FIGS. 1 to 3;

FIG. 6 is a perspective view of a ratchet ring forming part of the chuckof FIGS. 1 to 3;

FIG. 7 is a perspective view of a ratchet ring forming part of a chuckwith locking device according to a variant of the embodiment shown inFIGS. 1 to 3;

FIG. 8 is a partially sectioned side view of a chuck with locking deviceaccording to another embodiment of the present invention;

FIG. 9 is an exploded perspective view of the chuck of FIG. 8;

FIG. 10 is a partially sectioned perspective view of the chuck of FIGS.8 and 9;

FIG. 11 is a partially sectioned side view of a chuck with lockingdevice according to yet another embodiment of the present invention;

FIG. 12 is a partially sectioned side view of a chuck with lockingdevice according to an additional embodiment of the present invention;

FIG. 13 is an exploded perspective view of the chuck of FIG. 12; and

FIG. 14 is a perspective view of a ratchet ring forming part of thechuck of FIG. 13.

DETAILED DESCRIPTION OF EMBODIMENTS

First referring to FIGS. 1 to 3, the chuck with locking device of thepresent invention comprises, according to an embodiment, a base body 1having a central longitudinal axis E and being able to be connected to adrive shaft (not shown) for rotating therewith. The drive shaft canbelong to a machine, to a power tool or to a hand-powered tool, and itcan be able to rotate in both directions.

An outer casing 2 is coupled outside the base body 1 such that it canrotate coaxially but not move axially with respect to the base body 1.The outer casing 2 comprises a front fitting sleeve 21 and a rear sleeve22 fixedly connected to one another by a threaded coupling 23, 24. Jaws3 which are coupled to guides formed in a guide body 20 housed in thefront fitting sleeve 21 and immobilized with respect to the outer casing2 are located inside the front fitting sleeve 21, such that the jaws 3are movable with respect to the outer casing 2 and are communicated withan axial opening of the front fitting sleeve 21. The outer casing 2rotates with respect to the base body 1 in cooperation with rollingelements 25 arranged between the rear sleeve 22 and the base body 1. Therolling elements 25 are configured to withstand mainly axial loads.

The chuck includes a fitting mechanism linking movements of the outercasing 2 to movements of the jaws 3 to fit the jaws 3 to bits havingdifferent diameters. In this embodiment, the fitting mechanism is akeyless self-tightening mechanism comprising a pusher 4 coupled to thebase body 1 by a threaded coupling 31, 32 and coupled to the outercasing 2 such that it can slide axially but not rotate coaxially. Morespecifically, the pusher 4 has outer screw threads 31 coupled to innerscrew threads 32 formed in the base body 1, such that relative rotationbetween the pusher 4 and the base body 1 translates into axialdisplacement of the pusher 4.

The guides of the guide body 20 in which the jaws 3 are coupled areinclined in converging directions towards the central longitudinal axisE and the pusher 4 is coupled to the jaws 3 with the ability to operatethem, such that rotation of the outer casing 2 together with the pusher4 with respect to the base body 1 in a tightening direction moves thejaws 3 out of the front fitting sleeve 21 and towards the centrallongitudinal axis E, and rotation of the outer casing 2 together withthe pusher 4 with respect to the base body 1 in an opposite looseningdirection moves the jaws 3 into the front fitting sleeve 21, away fromthe central longitudinal axis E. The front fitting sleeve 21 has anouter surface provided with gripping embossments 27 facilitating amanual grip thereof.

Preferably, the base body 1 has an axial through hole 18 and the pusher4 has an axial through hole 19 aligned and communicated with said axialthrough hole 18 of the base body 1, which allows gripping rods insertedalong the entire length of the chuck with the jaws 3.

To prevent the grip of the jaws 3 from loosening when the drive shaftrotates the chuck in the mentioned loosening direction, the chuckincludes a locking device comprising a ratchet mechanism operated by alocking control sleeve 14 coupled outside the base body 1 at an endopposite the front fitting sleeve 21.

The ratchet mechanism comprises a toothed ring 5 formed at a rear end ofthe rear sleeve 22. This toothed ring has a plurality of asymmetricalteeth 5 a located radially in a plane perpendicular to the centrallongitudinal axis E. FIG. 5 illustrates the asymmetrical profile of theteeth 5 a, where each tooth has a rear face (in relation to the relativetightening rotation direction) forming a first angle A1 with respect toa direction D parallel to the central longitudinal axis E and a frontface forming a second angle A2 with respect to the direction D parallelto the central longitudinal axis E, the first angle A1 being larger thanthe second angle A2.

The ratchet mechanism further comprises a ratchet ring 9 (shown byitself in FIG. 6), which is obtained, for example, by press forming orby laser cutting from a spring steel sheet element. The ratchet ring 9has a planar annular body with a central hole 15, retaining tongues 17extending towards the central longitudinal axis E from an inner edge ofsaid central hole 15, and cuts defining three interlocking elastic tabs11 distributed at equal angular intervals around the ratchet ring 9. Theinterlocking elastic tabs 11 are bent such that they project in aninclined manner away from the planar annular body. Each of theinterlocking elastic tabs 11 has a free end providing a ratchet pawl 6.

The base body 1 has a cylindrical portion in an outer surface of whichretaining grooves 16 are formed (FIGS. 2 and 3) parallel to the centrallongitudinal axis E. This cylindrical portion of the base body 1 isinserted in a sliding manner through the central hole 15 of the ratchetring 9 with the retaining tongues 17 of the ratchet ring 9 inserted inthe retaining grooves 16. Therefore, the retaining tongues 17 incooperation with the retaining grooves 16 of the base body 1 preventrelative rotation between the ratchet ring 9 and the base body 1 butallow axial movement of the ratchet ring 9 with respect to the base body1.

The ratchet ring 9 is arranged adjacent to and facing the toothed ring5, and with the interlocking elastic tabs 11 oriented towards thetoothed ring 5. A releasing elastic element is arranged undercompression between the ratchet ring 9 and the toothed ring 5, saidreleasing elastic element being formed by a coil spring 28 having afirst end supported in a support surface 10 of the planar annular bodyof the ratchet ring 9 located between the interlocking elastic tabs 11and the central hole 15, and a second end supported in an annular seat29 formed in the outer casing 2 between the toothed ring 5 and the basebody 1. Therefore, the coil spring 28 permanently pushes the ratchetring 9 towards a direction of moving away from the toothed ring 5.

A locking ring 7 is arranged outside the base body 1 in a positionadjacent to the ratchet ring 9 on a side thereof opposite the toothedring 5. The locking ring has a support surface 7 a in contact with theratchet ring 9. A cam 8 is formed in a cylindrical side wall of thelocking ring 7.

As is best shown in FIG. 4, the cam 8 of the locking ring 7 is formed bya cam groove extending in a circumferential direction between a firstend 8 a and a second end 8 b. The first end 8 a of the cam groove iscloser in an axial direction to the support surface 7 a than the secondend 8 b. The cam groove furthermore has a first intermediate point 8 clocated closer in the circumferential direction to the first end 8 athan to the second end 8 b and farther away in the axial direction fromthe support surface 7 a than the second end 8 b, and a secondintermediate point 8 d located closer in the circumferential directionto the second end 8 b than to the first end 8 a and at the same distancein the axial direction from the support surface 7 a as the second end 8b. The cam groove defines between the first end 8 a and the firstintermediate point 8 c an inclined path with respect to the supportsurface 7 a, and between the second intermediate point 8 d and thesecond end 8 b a path parallel to the support surface 7 a.

A pin 13 is inserted in the cam groove, which constitutes the cam 8 ofthe locking ring 7, and in a hole 30 perpendicular to the centrallongitudinal axis E formed in the base body 1. The pin 13 has a diameterconjugate with a width of the cam groove such that the pin 13 can slidealong the cam 8. Therefore, the cam 8, in cooperation with the pin 13,determines axial movement of the locking ring 7 between an axial lockingposition and an axial release position when the locking ring 7 isrotated in relation to the base body 1 between an angular releaseposition, limited by the first end 8 a of the cam groove, and an angularlocking position, limited by the second end 8 b of the cam groove.

Therefore, when the locking control sleeve 14 is placed in the angularand axial locking position, the locking ring 7 presses the ratchet pawls6 against the toothed ring 5 in opposition to a force exerted by thecoil spring 28, and this blocks relative rotation between the base body1 and the outer casing 2 in a loosening direction for loosening the gripof the jaws 3 but allows relative rotation in a tightening direction fortightening the grip of the jaws 3 by virtue of the elasticity of theinterlocking elastic tabs 11. When the locking control sleeve 14 isplaced in the angular and axial release position, the locking ring 7allows the coil spring 28 to separate the ratchet pawls 6 from thetoothed ring 5, which allows free relative rotation between the basebody 1 and the outer casing 2 in both directions.

The compression of the coil spring 28 is greater in the angular lockingposition than in the angular release position. Nevertheless, to go fromthe angular locking position to the angular release position it isnecessary to overcome additional compression of the coil spring 28caused by a small ramp in the cam groove from the second intermediatepoint 8 d to first intermediate point 8 c, preventing unintentionalunlocking of the ratchet mechanism.

The aforementioned locking control sleeve 14 is fixed outside thelocking ring 7 and has an inner surface covering the cam groove of thecam 8 and retaining the pin 13 inserted in the cam groove and in thehole 30 of the base body 1. The locking control sleeve 14 has an outersurface provided with gripping embossments 26 facilitating a manual gripto rotate the locking control sleeve 14 together with the locking ring 7between the angular and axial release position, demarcated by the firstend 8 a of the cam groove, and the angular and axial locking position,demarcated by the second end 8 b of the cam groove.

FIG. 7 shows a ratchet ring 9 belonging to another embodiment (notshown) of the chuck of the present invention, which only differs fromthe embodiment described above in relation to FIGS. 1 to 6 in that thereleasing elastic element is formed by elastic spring tabs 12 derivedfrom ratchet ring 9 itself instead of by the coil spring 28.

The ratchet ring of FIG. 7 has cuts defining two interlocking elastictabs 11 located in diametrically opposed positions and additional cutsdefining two elastic spring tabs 12 arranged in diametrically opposedpositions intercalated between the interlocking elastic tabs 11. Boththe interlocking elastic tabs 11 and the elastic spring tabs 12 are bentsuch that they project in an inclined manner outwards and towards thesame side of the planar annular body. Each of the interlocking elastictabs 11 has a free end providing a ratchet pawl 6 configured forinterlocking in the asymmetrical teeth 5 a of the toothed ring 5, andeach of the elastic spring tabs 12 has a rounded end portion 12 aconfigured for resting on and slipping over the asymmetrical teeth 5 aof the toothed ring 5.

The rounded end portions 12 a of the elastic spring tabs 12 are arrangedat a greater axial distance from the planar annular body of the ratchetring 9 than the ratchet pawls 6 of the interlocking elastic tabs 11,such that when the locking control sleeve 14 is placed in the angularand axial unlocking position, the locking ring 7 allows a force exertedby the elastic spring tabs 12 to separate the ratchet pawls 6 from thetoothed ring 5, and when the locking control sleeve 14 is placed in theangular and axial locking position, the locking ring 7 presses theratchet pawls 6 against the asymmetrical teeth 5 a of the toothed ring 5in opposition to the force exerted by the elastic spring tabs 12.

FIGS. 8 to 10 show another alternative embodiment of the chuck withlocking device of the present invention, comprising a base body 1, anouter casing 2, three jaws 3 to grip a bit (not shown), a fittingmechanism linking movements of the outer casing 2 to movements of thejaws 3 to fit the jaws 3 to bits having different diameters, and alocking device.

The base body 1 has a central longitudinal axis E and is suitable forbeing connected to a drive shaft for rotating therewith. The outercasing 2 is coupled outside the base body 1 such that it can rotatecoaxially but not move axially with respect to the base body 1. The basebody 1 has an axial through hole 18 and three guide holes 44 distributedat regular intervals around the central longitudinal axis E and inclinedin converging directions towards the central longitudinal axis E. Theouter casing 2 has an axial opening.

The three jaws 3 are housed in a movable manner in the three guide holes44 such that they emerge through the axial opening of the outer casing2. The base body 1 has formed therein a circumferential groove 45 havingintersections 46 with the guide holes 44, and the jaws 3 have formedtherein thread teeth 43 that are exposed in the intersections 46.

The fitting mechanism comprises an actuator ring 41 fixed inside theouter casing 2. The actuator ring 41 is inserted in the circumferentialgroove 45 of the base body 1 and makes sliding contact with facingopposite surfaces of the circumferential groove 45, allowing the jointrotation of the actuator ring 41 and the outer casing 2 with respect tothe base body 1 and preventing axial displacement of the actuator ring41 and the outer casing 2 with respect to the base body 1. The actuatorring 41 is made in two halves 41 a, 41 b (FIG. 9) for the sole purposeof facilitating construction and assembly.

The actuator ring 41 has screw threads 42 meshing with the thread teeth43 of the jaws 3 in the intersections 46, such that rotation of theouter casing 2 together with the actuator ring 41 with respect to thebase body 1 in a tightening direction moves the jaws 3 towards thecentral longitudinal axis E, and rotation of the outer casing 2 togetherwith the actuator ring 41 with respect to the base body 1 in an oppositeloosening direction moves the jaws 3 away from the central longitudinalaxis E.

The locking device is similar to the one described above in relation toFIGS. 1 to 3 and comprises a ratchet mechanism operated by a lockingcontrol sleeve 14 coupled outside the base body 1 such that it canrotate between angular locking and release positions in cooperation witha cam 8 and a releasing elastic element. When the locking control sleeve14 is in the angular locking position, the ratchet mechanism blocksrelative rotation between the base body 1 and the outer casing 2 in aloosening direction for loosening the grip of the jaws 3 but allowsrelative rotation in a tightening direction for tightening the grip ofthe jaws 3, and when the locking control sleeve 14 is in the angularrelease position, the ratchet mechanism allows relative rotation betweenthe base body 1 and the outer casing 2 in both directions.

The ratchet mechanism comprises a toothed ring 5, a ratchet ring 9, alocking ring 7, and a releasing elastic element. The toothed ring 5 hasa plurality of asymmetrical teeth 5 a and is fixed with respect to theouter casing 2.

The ratchet ring 9, which is similar to the one shown in FIG. 6, is madeof sheet metal and has a central hole 15 and one or more interlockingelastic tabs 11 providing ratchet pawls 6 facing the asymmetrical teeth5 a of the toothed ring 5. Retaining tongues 17 which are inserted inretaining grooves 16 parallel to the central longitudinal axis E thatexist in a cylindrical portion of the base body 1 extend from an inneredge of the central hole 15, such that the ratchet ring 9 can slideaxially but not rotate coaxially with respect to the base body 1.

The locking ring 7 is arranged outside the base body 1 and fixed insidethe locking control sleeve 14 in a position adjacent to a side of theratchet ring 9 opposite the toothed ring 5. In this embodiment, thereleasing elastic element is formed by a coil spring 28 arranged undercompression between the ratchet ring 9 and an annular seat 47 formed inthe base body 1, such that the coil spring 28 permanently pushes theratchet ring 9 towards a direction of moving away from the toothed ring5. Alternatively, the releasing elastic element can be formed by elasticspring tabs 12 derived from the ratchet ring 9 as described above inrelation to FIG. 7.

The mentioned cam 8 comprises a cam groove formed in a wall of thelocking ring 7. A pin 13 is inserted in the cam groove and in a hole 30perpendicular to the central longitudinal axis E formed in the base body1. The cam 8 is similar to the one described above in relation to FIG.8. When the locking ring 7 is rotated with respect to the base body 1together with the locking control sleeve 14, the cam 8 determines axialmovement of the locking ring 7 between an axial locking position incorrespondence with the angular locking position and an axial releaseposition in correspondence with the angular release position.

When the locking ring 7 is in the axial locking position, the lockingring 7 presses the ratchet pawls 6 against the toothed ring 5 inopposition to a force exerted by the releasing elastic element, and whenthe locking ring 7 is in the axial release position, the locking ring 7allows the force exerted by the releasing elastic element to separatethe ratchet pawl 6 from the toothed ring 5.

The locking control sleeve 14 and the outer casing 2 have respectiveouter surfaces provided with gripping embossments 26, 27 facilitating amanual grip.

FIG. 11 shows yet another alternative embodiment of the chuck withlocking device of the present invention, which combines aself-tightening fitting mechanism with a key mechanism.

The hybrid chuck of FIG. 11 comprises a base body 1, an outer casing 2,three jaws 3, a fitting mechanism linking movements of the outer casing2 to movements of the jaws 3 to fit the jaws 3 to bits having differentdiameters, and a locking device.

The fitting mechanism is a self-tightening mechanism similar to the onedescribed above in relation to FIGS. 1 to 3, and comprises a pusher 4coupled inside the base body 1 by a threaded coupling 31, 32 and coupledto the outer casing 2 such that it can slide axially but not rotatecoaxially, such that relative rotation between the pusher 4 and the basebody 1 in one direction translates into axial displacement of the pusher4, moving the jaws 3 towards the central longitudinal axis E, andrelative rotation between the pusher 4 and the base body 1 in anopposite loosening direction moves the jaws 3 away from the centrallongitudinal axis E.

The locking device is similar to the one described above in relation toFIGS. 1 to 3 and comprises a ratchet mechanism operated by a lockingcontrol sleeve 14 in cooperation with a cam 8 (best shown in FIG. 4) anda releasing elastic element. The locking control sleeve 14 is coupledoutside the base body 1 such that it can rotate between an angularlocking position and an angular release position. The locking controlsleeve 14 and the outer casing 2 have respective outer surfaces providedwith gripping embossments 26, 27 facilitating a manual grip.

The cam 8 comprises a cam groove formed in a locking ring 7 and a pin 13inserted in the cam groove and in a hole 30 perpendicular to the centrallongitudinal axis E formed in the base body 1. The cam 8 determinesaxial movement of the locking ring 7 between axial locking and releasepositions when the locking ring 7 is rotated by the locking controlsleeve 14 coaxially with respect to the base body 1.

The ratchet mechanism comprises a toothed ring 5 formed at a rear end ofthe rear sleeve 22, and a ratchet ring 9 provided with interlockingelastic tabs 11 providing ratchet pawls 6 (best shown in FIG. 6). Theratchet pawls 6 interlock in the toothed ring 5 when the ratchet ring 9is pushed by the locking ring 7 into the axial locking position.

The releasing elastic element is formed by a coil spring 28 undercompression arranged between the ratchet ring 9 and an annular seat 29formed in the outer casing 2. Alternatively, the releasing elasticelement under compression can be formed by elastic spring tabs 12 formedin the ratchet ring 9 (FIG. 7), instead of the coil spring 28.

Additionally, the hybrid chuck with locking device of FIG. 11 isprepared for being able to tighten and loosen the jaws 3 using anauxiliary key 50 of a conventional type, which comprises a rod 53 endingin an end boss 51, and a bevel pinion 52 adjacent and coaxial to the endboss 51. The rod 53 has a cross-piece 54 or another protruding elementfacilitating the manual application of torque to the rod 53 connectedthereto.

A bevel crown wheel 33 is formed on a front edge of the locking controlsleeve 14, and a radial key guide hole 34 is formed in the rear sleeve22 of the outer casing 2. The radial key guide hole 34 is located withrespect to the bevel crown wheel 33 such that when the end boss 51 ofthe auxiliary key 50 is inserted in the radial key guide hole 34 thebevel pinion 52 of the auxiliary key 50 meshes with the bevel crownwheel 33. In this position, rotation of the auxiliary key 50 in atightening direction imparts rotation of the base body 1 with respect tothe outer casing 2 to move the jaws 3 to the closed position, androtation of the auxiliary key 50 in an opposite release directionimparts rotation of the base body 1 with respect to the outer casing 2to loosen the jaws 3 and move them to the open position.

An additional embodiment of the chuck with locking device of the presentinvention is now described with reference to FIGS. 12-14. The chuck withlocking device shown in FIGS. 12-14 only differs from the embodimentdescribed above with reference to FIGS. 1-7 in that the ratchet ring 9is made of solid material, such as for example solid metal, and has anannular body and a plurality of teeth 9 a protruding from the annularbody and facing the asymmetrical teeth 5 a of the toothed ring 5. Theteeth 9 a of the solid material ratchet ring 9 are complementary to theasymmetrical teeth 5 a of the toothed ring 5. A pressing elastic element48 is arranged under compression between the ratchet ring 9 and thelocking ring 7.

The asymmetrical profile of the teeth and the elasticity of the pressingelastic element 48 allows the ratchet ring 9 to retract away from thetoothed ring 5 and thereby disengage the teeth 9 a of the solid materialratchet ring 9 from the asymmetrical teeth 5 a of the toothed ring 5when the locking device is in the locking position and the outer casing2 is rotated relative to the base body 1 in a tightening direction fortightening the grip of the jaws 3.

In the shown example, the pressing elastic element 48 is a wave ringspring having a first end supported on a support surface of the lockingring 7 and a second end supported on the ratchet ring 9, and thereleasing elastic element is a coil spring 28 having a first endsupported in the ratchet ring 9 and a second end supported in an annularseat 29 formed in the outer casing 2. Alternatively the pressing elasticelement and the releasing elastic element can be of any other typeprovided that they dimensionally fit the chuck components and have anadequate elasticity coefficient.

The scope of the present invention is defined by the attached claims.

1. A chuck with locking device, comprising: a base body having a centrallongitudinal axis and being connectable for rotating with a drive shaft;an outer casing coupled outside said base body such that it can rotatecoaxially but not move axially with respect to the base body, said outercasing having an axial opening; a plurality of jaws arranged movablywith respect to the base body and the outer casing communicated withsaid axial opening; a fitting mechanism linking movements of the outercasing to movements of the jaws, such that rotation of the outer casingwith respect to the base body in a tightening direction moves the jawstowards said central longitudinal axis and rotation of the outer casingwith respect to the base body in an opposite loosening direction movesthe jaws away from the central longitudinal axis; and a locking devicecomprising a ratchet mechanism operated by a locking control sleevecoupled outside the base body such that it can rotate between angularlocking and release positions in cooperation with a cam and an elasticelement, where said ratchet mechanism, when said locking control sleeveis in said angular locking position, blocks relative rotation betweenthe base body and the outer casing in a loosening direction forloosening the grip of the jaws but allows relative rotation in atightening direction for tightening the grip of the jaws, and when thelocking control sleeve is in said angular release position, it allowsrelative rotation between the base body and the outer casing in bothdirections, characterized in that the ratchet mechanism comprises: atoothed ring that is fixed with respect to the outer casing, saidtoothed ring having a plurality of asymmetrical teeth; a ratchet ringfacing the toothed ring and arranged such that the ratchet ring canslide axially but not rotate coaxially with respect to the base body,said ratchet ring comprising an annular body and one or more tabsratchet pawls or teeth projecting from said annular body towards saidasymmetrical teeth of the toothed ring, said elastic element being areleasing elastic element arranged under compression between the ratchetring and the toothed ring; a locking ring arranged outside the base bodyand fixed inside to the locking control sleeve in a position adjacent tothe ratchet ring on a side thereof opposite the toothed ring; said camcomprising a cam groove formed in a wall of the locking ring and a pininserted in said cam groove and in a hole perpendicular to the centrallongitudinal axis formed in the base body, the cam determining axialmovement of the locking ring between axial locking and release positionscorresponding to the angular locking and release positions,respectively, when the locking ring is rotated by the locking controlsleeve coaxially with respect to the base body; wherein the lockingring, when it is in said axial locking position, presses said ratchetpawls or teeth against the toothed ring in opposition to a force exertedby said releasing elastic element, and when it is in said axial releaseposition, it allows said force exerted by the releasing elastic elementto separate the ratchet pawls or teeth from the toothed ring.
 2. Thechuck with locking device according to claim 1, wherein the ratchet ringis made of solid material, said teeth of the ratchet ring arecomplementary to the asymmetrical teeth of the toothed ring, and apressing elastic element is arranged under compression between theratchet ring and the locking ring.
 3. The chuck with locking deviceaccording to claim 1, wherein the ratchet ring is an annular body madeof steel spring sheet metal and the annular body has cuts defininginterlocking elastic tabs projecting from the annular body inclinedtowards the asymmetrical teeth of the toothed ring and having arespective free ends providing a said ratchet pawls.
 4. The chuck withlocking device according to claim 1, wherein said fitting mechanismcomprises a pusher coupled to the base body by a threaded coupling andcoupled to the outer casing such that it can slide axially but notrotate coaxially, said pusher being operatively coupled with said jaws,such that rotation of the outer casing together with said pusher withrespect to the base body in a tightening direction moves the jawstowards said central longitudinal axis and rotation of the outer casingtogether with the pusher with respect to the base body in an oppositeloosening direction moves the jaws away from the central longitudinalaxis.
 5. The chuck with locking device according to claim 1, whereinsaid fitting mechanism comprises an actuator ring fixed inside the outercasing, said actuator ring having screw threads coupled to thread teethformed in said jaws, such that rotation of the actuator ring withrespect to the base body in a tightening direction moves the jawstowards said central longitudinal axis and rotation of the actuator ringwith respect to the base body in an opposite loosening direction movesthe jaws away from the central longitudinal axis.
 6. The chuck withlocking device according to claim 1, wherein the locking control sleevehas an inner surface covering the cam groove and retaining said pininserted in the cam groove and in said hole of the base body.
 7. Thechuck with locking device according to claim 1, wherein the releasingelastic element is formed by a coil spring having a first end supportedin the ratchet ring and a second end supported in an annular seat formedin the outer casing.
 8. The chuck with locking device according to claim1, wherein the releasing elastic element is formed by a coil springhaving a first end supported in the ratchet ring and a second endsupported in an annular seat formed in the base body.
 9. The chuck withlocking device according to claim 3, wherein the releasing elasticelement is formed by one or more elastic spring tabs defined byadditional cuts formed in the ratchet ring and projecting from theratchet ring inclined towards the toothed ring, each of the elasticspring tabs having a rounded end portion resting on the asymmetricalteeth of the toothed ring, said rounded end portions being arranged at agreater axial distance from the ratchet ring than the ratchet pawls ofthe interlocking elastic tabs.
 10. (canceled)
 11. The chuck with lockingdevice according to claim 1, wherein the base body has a cylindricalportion inserted through a central hole of the ratchet ring, saidcylindrical portion of the base body has an outer surface in which atleast one retaining groove parallel to the central longitudinal axis isformed, the ratchet ring has at least one retaining tongue extendingtowards the central longitudinal axis from an inner edge of said centralhole of the ratchet ring, and said retaining tongue is inserted in saidretaining groove of the base body preventing relative rotation betweenthe ratchet ring and the base body.
 12. The chuck with locking deviceaccording to claim 1, wherein the cam groove comprised in the camextends in a circumferential direction between a first end and a secondend, said first end being closer in an axial direction to a supportsurface of the locking ring adjacent to the ratchet ring than saidsecond end.
 13. The chuck with locking device according to claim 12,wherein the cam groove comprised in the cam furthermore has a firstintermediate point located closer in said circumferential direction tothe first end than to the second end and farther away in said axialdirection from said support surface than the second end, and a secondintermediate point located closer in the circumferential direction tothe second end than to the first end and at the same distance in theaxial direction from the support surface as the second end.
 14. Thechuck with locking device according to claim 4, wherein the base bodyhas an axial through hole and the pusher has an axial through holealigned and communicated with said axial through hole of the base body.15. The chuck with locking device according to claim 4, wherein theouter casing comprises a front fitting sleeve in which the jaws arehoused and a rear sleeve having a rear end in which the asymmetricalteeth of the toothed ring are formed, said front fitting sleeve and saidrear sleeve being fixedly connected to one another by a threadedcoupling.
 16. The chuck with locking device according to claim 15,wherein the jaws are coupled to guides formed in a guide body housed inthe front fitting sleeve and immobilized with respect to the outercasing.
 17. The chuck with locking device according to claim 15, whereinthe outer casing rotates with respect to the base body in cooperationwith rolling elements arranged between the rear sleeve and the base bodyto withstand axial loads.
 18. The chuck with locking device according toclaim 4, wherein the pusher has outer screw threads coupled to innerscrew threads formed in the base body (1).
 19. (canceled)
 20. The chuckwith locking device according to claim 5, wherein the jaws are housed inguide holes formed in the base body, said guide holes being inclined inconverging directions towards the central longitudinal axis, and whereinthe actuator ring is inserted in a circumferential groove formed in thebase body, there being in said circumferential groove openingscommunicated with the guide holes. 21-24. (canceled)
 25. The chuck withlocking device according to claim 15, wherein the locking control sleevehas a bevel crown wheel and the rear sleeve of the outer casing has aradial key guide hole, where said radial key guide hole is configuredand arranged to receive an end boss of an auxiliary key and said bevelcrown wheel is configured and arranged to mesh with a bevel pinion ofsaid auxiliary key when said end boss of the auxiliary key is insertedin said radial key guide hole.
 26. A chuck with locking device,comprising: a base body having a central longitudinal axis and beingconnectable for rotating with a drive shaft; an outer casing coupledoutside said base body such that it can rotate coaxially but not moveaxially with respect to the base body, said outer casing having an axialopening; a plurality of jaws arranged movably with respect to the basebody and the outer casing communicated with said axial opening; afitting mechanism linking movements of the outer casing to movements ofthe jaws, such that rotation of the outer casing with respect to thebase body in a tightening direction moves the jaws towards said centrallongitudinal axis and rotation of the outer casing with respect to thebase body in an opposite loosening direction moves the jaws away fromthe central longitudinal axis; and a locking device comprising a ratchetmechanism operated by a locking control sleeve coupled outside the basebody such that it can rotate between angular locking and releasepositions in cooperation with a cam and an elastic element, where saidratchet mechanism, when said locking control sleeve is in said angularlocking position, blocks relative rotation between the base body and theouter casing in a loosening direction for loosening the grip of the jawsbut allows relative rotation in a tightening direction for tighteningthe grip of the jaws, and when the locking control sleeve is in saidangular release position, it allows relative rotation between the basebody and the outer casing in both directions, wherein the ratchetmechanism comprises: a toothed ring that is fixed with respect to theouter casing, said toothed ring having a plurality of asymmetricalteeth; a ratchet ring facing the toothed ring and arranged such that theratchet ring can slide axially but not rotate coaxially with respect tothe base body, said ratchet ring comprising an annular body made ofsolid material and teeth projecting from said annular body towards saidasymmetrical teeth of the toothed ring, said elastic element being areleasing elastic element arranged under compression between the ratchetring and the toothed ring; a locking ring arranged outside the base bodyand fixed inside to the locking control sleeve in a position adjacent tothe ratchet ring on a side thereof opposite the toothed ring, a pressingelastic element being arranged under compression between the ratchetring and the locking ring; said cam comprising a cam groove formed in awall of the locking ring and a pin inserted in said cam groove and in ahole perpendicular to the central longitudinal axis formed in the basebody, the cam determining axial movement of the locking ring betweenaxial locking and release positions corresponding to the angular lockingand release positions, respectively, when the locking ring is rotated bythe locking control sleeve coaxially with respect to the base body;wherein the locking ring, when it is in said axial locking position,presses said teeth against the toothed ring in opposition to a forceexerted by said releasing elastic element, and when it is in said axialrelease position, it allows said force exerted by the releasing elasticelement to separate the teeth from the toothed ring.
 27. The chuck withlocking device according to claim 26, wherein said fitting mechanismcomprises a pusher coupled to the base body by a threaded coupling andcoupled to the outer casing such that it can slide axially but notrotate coaxially, said pusher being operatively coupled with said jaws,such that rotation of the outer casing together with the pusher withrespect to the base body in a tightening direction moves the jawstowards said central longitudinal axis and rotation of the outer casingtogether with the pusher with respect to the base body in an oppositeloosening direction moves the jaws away from the central longitudinalaxis.